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Microbio Ex 1 > Ex 2- Virus Classification, Structure, & Replication- Middleton > Flashcards

Ex 2- Virus Classification, Structure, & Replication- Middleton Flashcards

1
Q

What is the difference btw virus and bacterium?

A
  • bacteria replicate on own

- virus require host to replicate

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2
Q

What is the difference btw a virus and a toxin?

A
  • virus can replicate w/ host

- toxin cannot replicate

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3
Q

_____ and _____ disease was the first animal virus discovered

A

foot and mouth

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4
Q

______ _____ virus was the first human virus discovered in 1901

A

yellow fever

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5
Q

Viruses are _____ than bacteria, fungus, and other microorganisms

A

smaller

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6
Q

Viruses replicate when provided a _______

A

host

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7
Q

Viruses are obligate intracellular ______ and not autopoietic

A

parasites

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8
Q

virus means “_____” in Greek

A

poision

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9
Q

Viruses are _______ to nature and don’t always cause disease

A

ubiquitious

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10
Q

What are the 2 theories of virus origin?

A
  • cellular

- autopoietic

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11
Q

The ______ origin theory proposes that viruses were once cellular components but over time they evolved separately

A

cellular

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12
Q

The _____ origin theory proposes that viruses, once autopoietic entities, became dependent on cells for replication

A

autopoietic

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13
Q

What attributes are used for virus classification?

A
  • particle structure
  • genome
  • replication features
  • serology (antibodies)
  • stability (heat, chemicals)
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14
Q

Virus particles can be classified by what 3 things?

A
  • composition
  • shape
  • size
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15
Q

_______ is RNA or DNA in a core that is protected by a protein coat (capsid)

A

nucleocapsid

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16
Q

A virus can be defined by the ________ structure

A

nucleocapsid

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17
Q

What are three types of nucleocapsid structures based on symmetry?

A
  • helical
  • pleomorphic
  • icosahedral
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18
Q

A nucleocapsid is comprised of repeating protein subunits (1,2 or 3)called ________

A

capsomeres

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19
Q

________ are virus-modified cellular membranes acquired upon exit from host

A

envelopes

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20
Q

Exposure to _____ solvents renders enveloped viruses noninfectious

A

lipid (ie alcohol, ether,acetone, Freon, etc)

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21
Q

Enveloped viruses may have ______ with different structures

A

nucleocapsids

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22
Q

____ nm is the smallest virus particle and _____ nm is the largest virus particle

A
  • 18 nm

- 300 nm (almost size of bacteria)

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23
Q

What are the advantages of having a small size?

A
  • small genomes can replicate quicker
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24
Q

What are the advantages of having a large size?

A
  • large genomes carry more genes + proteins (immune modulators) that downregulate innate immunity
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25
Q

What are the different compositions of a viral genome?

A

double or single stranded DNA or RNA

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26
Q

What are the different types of single stranded RNA?

A

(+)ssRNA
(-)ssRNA
Ambisense

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27
Q

(__) ssRNA can be used directly for the translation of proteins

A

(+)

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28
Q

(__) ssRNA has to make (__) sense copy to replicate

A

(-)

+

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29
Q

____ ssRNA has portions that are minus and plus sense

A

ambisense

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30
Q

What are the different structures (gene arrangements) of the viral genome?

A
  • linear
  • circular
  • segmented
  • dipoloid
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31
Q

Why do viruses do not have to follow the central dogma of DNA-RNA-protein?

A

Reverse transcriptase which allows reverse transcription (RNA to DNA)

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32
Q

What is required for replication of a virus to begin?

A

ssDNA hairpin, signals for cellular machinery to copy

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33
Q

Herpesvirus requires ____ _____ ____ to initiate replication

A

dsDNA rolling circle

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34
Q

Picornavirus is a ( )ssRNA that sits on ribosomes and starts replication

A

(+)ssRNA

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35
Q

(-)ssRNA needs ____ dependent ___ plymerase to replicate

A

RNA

RNA

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36
Q

What do DNA viruses needed to replicate?

A

nucleus- needs host cell machinery

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37
Q

RNA viruses need ____ _______ ______ ____ to replicate

A

RNA dependent RNA polymerase

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38
Q

What are the 7 steps to virus replication?

A
  • attachment
  • entry
  • transcription
  • translation
  • replication
  • assembly
  • release
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39
Q

How do viruses attach to a cell?

A

binding or virus receptor to cellular receptor (our functional cells) bc cells do not have virus receptors

40
Q

What type of cell receptors do viruses bind to?

A
  • signaling molecules
  • cell adhesion
  • transport
41
Q

How do viral receptors attach to cell receptor?

A
  • spike like projections on particle surface

- may require co-receptor

42
Q

______ is a major determinant of virus tropism (host range)

A

Attachment

43
Q

Viruses infect essentially ___ known forms of life

A

all

44
Q

______ is the term for viruses that can infect humans and animals, which are not shared across more divergent hosts

A

zoonosis

45
Q

_____ _____ is a major factor in eradication

A

host range

46
Q

Viruses do not cross ______

A

kingdoms

47
Q

What are the 2 pathways of viral entry?

A
  • receptor mediated endocytosis

- direct penetration of plasma membrane

48
Q

What are the pathways that non-enveloped viruses enter the cell?

A
  • pores (picornavirus)

- membrane disruption (adenovirus, reovirus)

49
Q

What are the pathways that enveloped viruses enter the cell?

A
  • membrane fusion

- receptor conformational change (pH, receptor induced)

50
Q

What happens during nuclear replication?

A
  • genome and remaining protein coat (nucleocapsid) transported to nuclear membrane and deliver the genome to the nucleus
51
Q

What happens during cytoplasmic replication?

A
  • genome released in cytoplasm and transported to intracellular site of replication
52
Q

May RNA viruses replicate in _______ _______ complexes

A

membrane associated

53
Q

dsRNA viruses never release their______ _____ from the entering particle

A

-genomic material, bc would cause signaling for innate immune system

54
Q

Transcription results in the production of ______ templates for protein synthesis

A

mRNA

55
Q

DNA viruses rely upon cellular _____ polymerases for transcription

A

RNA

56
Q

The genome of (__)ssRNA viruses can serve as mRNA

A

(+)

57
Q

( _) ssRNA and dsRNA viruses must bring in their own _____ into the cell

A
  • (-)

- polymerases

58
Q

ALL viruses need the cell’s _____ to produce protein bc they do not have them

A

ribosomes

59
Q

Viral protein production can be regulated at the ________ level or _____ level

A
  • transcript (mRNA)

- translation

60
Q

Structural proteins are produced in _____ quantities and non-structural proteins are only seen ____ the infected cell

A
  • high

- inside

61
Q

The objective of virus ______ is to make additional genome copies

A

replication

62
Q

The order of genomic replication of viruses depends on virus ______

A

genome

63
Q

(+)ssRNA polymerase makes (__)ssRNA copy as template for new genomes

A

(-)

64
Q

(__) ssRNA genomes replicate through full-length (__)ssRNA intermediate

A

(-)

+

65
Q

_____ induces innate immune response so genome stays inside particle which has viral polymerase

A

dsRNA

66
Q

The mRNA of dsRNA is synthesized in the _____ and exported to the ______

A
  • particle

- cytoplasm

67
Q

ssDNA and dsDNA must gain access to the _____

A

nucleus

68
Q

_____ are a nexception bc the virion contains necessary info (RNA polymerase and genome encodes DNA polymerase for replication) to replicate in the cytoplasm

A

poxvirus

69
Q

During viral ______ new genomes are packaged into functional particles

A

assembly

70
Q

______ ______ proteins aid in assembly and the genome contains packaging signals

A

localized structural

71
Q

What is the mechanism for assembly in adenovirus?

A
  • empty protein coat imports genome
72
Q

What is the mechanism for assembly in a reovirus?

A

RNA packaged during capsid assembly

73
Q

What is the mechanism for assembly in a reterovirus?

A

preassembly on membrane

74
Q

What are the different types of viral releases?

A
  • lysis
  • weak lysis
  • budding (enveloped only)
75
Q

____ is best known for bateriophage and is when viral molecules rupture the cellular membrane

A

lysis

76
Q

What is the disadvantage of lysis?

A

viral particles released trigger immune response

77
Q

What is a disadvantage of targeting viral replication in the nucleus?

A

must cross 2 membranes

78
Q

During a ____ step growth curve viruses infect every cell at the same time and every cell dies at the end of infection

A

one

79
Q

What are the 3 kinetic phases of virus replication?

A
  • eclipse; attachment and uptake
  • exponential growth; replication and assembly
  • plateau; cell death bc no nucletoides or AA, exhausted resources
80
Q

What is the length of time from the start of infection to beginning of plateau in bacteriophage, vesicular stomatitis virus, and vaccinia?

A

bacteriophage; 30 min
VSV; 6hrs
vaccinia; 24 hrs

81
Q

Productivity of a virus is measured by ______

A

amplification
VSV 1:1000
Vaccinia 1:100

82
Q

What methods rare used to initially discover viruses?

A
  • disease in host

- contaminant in cell culture

83
Q

What are the methods for confirmation of a virus?

A
  • purification of virus
    -confirmation of disease
    (animals,eggs, cell culture-preferred)
84
Q

What are the principle of detection and quantification methods?

A
  • infectivity
  • physical
  • genome
  • serological
85
Q

_____ methods are useful for viruses that cannot be cultivated

A

molecular

86
Q

What are the 4 types of infection assays?

A
  • infection assays
  • particle assay
  • genome
  • serological
87
Q

What are the 4 types of infection assays?

A
  • cytopathic effect(CPE)
  • fluorescent focus
  • plaque assay
  • infectious dose
88
Q

What are the two types of particle assays?

A
  • electron microscopy

- hamagglutinin assay

89
Q

What are the 2 types of genome assays?

A
  • PCR

- southern (DNA) & Northern (RNA)

90
Q

What are the 3 types of serological assays?

A
  • virus neutralization
  • enzyme link immunosorbant assay (ELISA)
  • Western (protein) blot
91
Q

Different methods of virus detection and quantification give _____ answers?

A

different

92
Q

How many infectious viruses do you have?

A

particle to PFU ranges from 1:1 to 1:10,000

93
Q

Viruses are “alive” inside ____ only

A

cells

94
Q

Human viruses have diameters of ___- ____ nm

A

30-300nm

95
Q

Viruses are classified by ____, ____ ____ structure, and _____ stragegy

A

genome, virus particle structure, replication strategy

Microbio Ex 1 (18 decks)

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